Answer by Ben Wex for How to include files outside of Docker's build context?

An easy workaround might be to simply mount the volume (using the -v or --mount flag) to the container when you run it and access the files that way.

example:

docker run -v /path/to/file/on/host:/desired/path/to/file/in/container/ image_name

for more see: https://docs.docker.com/storage/volumes/